Obs. : 2009-02-25 Planet Ly alpha (photons/cm^2/sec) Mercury 3.405e+11 Venus 3.471e+11 Earth 3.428e+11 Mars 3.405e+11 Jupiter 3.405e+11 Saturn 3.389e+11 Uranus 3.496e+11 Neptune 3.469e+11 Pluto 3.359e+11